Compliance after switching from CPAP to bilevel for patients with non-compliant OSA: big data analysis

Introduction

For patients with obstructive sleep apnoea (OSA) who are initially non-compliant with continuous (automatic) positive airway pressure (CPAP/APAP) therapy, a bilevel PAP (Spont/VAuto) therapy transition pathway is available to improve therapy adherence. The aim of this retrospective study was to compare PAP therapy usage data of patients with non-compliant OSA (ncOSA) on CPAP/APAP who were switched to bilevel PAP.

Methods

A PAP telemonitoring database was queried between 1 January 2015 and 31 July 2016 for eligible patients started on CPAP/APAP and non-CMS (United States Center for Medicare and Medicaid Services) compliant and switched to bilevel PAP within 90 days of starting CPAP/APAP therapy. PAP therapy data on all patients were compared before switch (CPAP/APAP) and after switch (VAuto/Spont).

Results

Of the 1496 patients with ncOSA identified, 30.3% used CPAP, 62.3% APAP, and 7.4% both APAP and CPAP before switching to a bilevel mode. 47.8% patients switched to Spont mode and 52.2% to VAuto mode. PAP usage significantly improved by 0.9 h/day (p<0.001) and all other device metrics (residual apnoea–hypopnoea index and unintentional mask leak) also improved after the switch. No patients had achieved US CMS criteria for compliance before the switch, and 56.8% did after.

Conclusion

This shows for the first time that there may be potential benefit from switching from CPAP/APAP to bilevel PAP for patients struggling with PAP adherence.

A Global Comparison of Anatomic Risk Factors and Their Relationship to Obstructive Sleep Apnea Severity in Clinical Samples

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is a global health issue and is associated with obesity and oropharyngeal crowding. Global data are limited on the effect of ethnicity and sex on these relationships. We compare associations between the apnea-hypopnea index (AHI) and these risk factors across ethnicities and sexes within sleep clinics.

METHODS

This is a cross-sectional, multicenter study of patients with OSA from eight sleep centers representing the Sleep Apnea Global Interdisciplinary Consortium (SAGIC). Four distinct ethnic groups were analyzed, using a structured questionnaire: Caucasians (Australia, Iceland, Germany, United States), African Americans (United States), Asians (Taiwan), and South Americans (Brazil). Regression analyses and interaction tests were used to assess ethnic and sex differences in relationships between AHI and anthropometric measures (body mass index [BMI], neck circumference, waist circumference) or Mallampati score.

RESULTS

Analyses included 1,585 individuals from four ethnic groups: Caucasian (60.6%), African American (17.5%), Asian (13.1%), and South American (8.9%). BMI was most strongly associated with AHI in South Americans (7.8% increase in AHI per 1 kg/m² increase in BMI; P < .0001) and most weakly in African Americans (1.9% increase in AHI per 1 kg/m² increase in BMI; P = .002). In Caucasians and South Americans, associations were stronger in males than females. Mallampati score differed between ethnicities but did not influence AHI differently across groups.

CONCLUSIONS

We demonstrate ethnic and sex variations in associations between obesity and OSA. For similar BMI increases, South American patients show greatest AHI increases compared to African Americans. Findings highlight the importance of considering ethnicity and sex in clinical assessments of OSA risk.

Sleep Quality and Fatigue Are Associated with Pain Exacerbations of Hip Osteoarthritis: An Internet-based Case-crossover Study

OBJECTIVE

To evaluate the association of sleep quality, sleep duration, and fatigue with hip pain exacerbations in persons with symptomatic hip osteoarthritis (OA).

METHODS

Participants (n = 252) were followed for 90 days and asked to complete online questionnaires at 10-day intervals (control periods). A hip pain exacerbation (case periods) was defined as an increase of 2 points in pain intensity compared with baseline on a numeric rating scale (0-10). Subjective sleep quality and sleep duration were assessed using the Pittsburgh Sleep Quality Index, and fatigue was measured by Multidimensional Assessment of Fatigue in both periods. Univariable and multivariable conditional logistic regressions were used to assess the association.

RESULTS

Of the 252 participants, 130 (52%) were included in the final analysis. Univariate association analysis showed that both poor sleep quality and greater fatigue were associated with increased odds of pain exacerbations (OR 1.72, 95% CI 1.04-2.86; OR 1.92, 95% CI 1.21-3.05, respectively). Short sleep duration was not associated with pain exacerbations. Poor sleep quality and greater fatigue remained associated with pain exacerbations after adjustment for physical activity and night pain levels in multivariable analysis. There was no significant interaction between sleep quality and fatigue (p = 0.21).

CONCLUSION

Poor sleep quality and greater fatigue were related to pain exacerbation in persons with symptomatic hip OA. Sleep disorders and fatigue should be considered when dealing with pain exacerbations.

Positive airway pressure for sleep-disordered breathing in acute quadriplegia: a randomised controlled trial

RATIONALE

Highly prevalent and severe sleep-disordered breathing caused by acute cervical spinal cord injury (quadriplegia) is associated with neurocognitive dysfunction and sleepiness and is likely to impair rehabilitation.

OBJECTIVE

To determine whether 3 months of autotitrating CPAP would improve neurocognitive function, sleepiness, quality of life, anxiety and depression more than usual care in acute quadriplegia.

METHODS AND MEASUREMENTS

Multinational, randomised controlled trial (11 centres) from July 2009 to October 2015. The primary outcome was neurocognitive (attention and information processing as measure with the Paced Auditory Serial Addition Task). Daytime sleepiness (Karolinska Sleepiness Scale) was a priori identified as the most important secondary outcome.

MAIN RESULTS

1810 incident cases were screened. 332 underwent full, portable polysomnography, 273 of whom had an apnoea hypopnoea index greater than 10. 160 tolerated at least 4 hours of CPAP during a 3-day run-in and were randomised. 149 participants (134 men, age 46±34 years, 81±57 days postinjury) completed the trial. CPAP use averaged 2.9±2.3 hours per night with 21% fully 'adherent' (at least 4 hours use on 5 days per week). Intention-to-treat analyses revealed no significant differences between groups in the Paced Auditory Serial Addition Task (mean improvement of 2.28, 95% CI -7.09 to 11.6; p=0.63). Controlling for premorbid intelligence, age and obstructive sleep apnoea severity (group effect -1.15, 95% CI -10 to 7.7) did not alter this finding. Sleepiness was significantly improved by CPAP on intention-to-treat analysis (mean difference -1.26, 95% CI -2.2 to -0.32; p=0.01).

CONCLUSION

CPAP did not improve Paced Auditory Serial Addition Task scores but significantly reduced sleepiness after acute quadriplegia.

TRIAL REGISTRATION NUMBER

ACTRN12605000799651.

Associations Between Obstructive Sleep Apnea and Measures of Arterial Stiffness

STUDY OBJECTIVES

The aim of this study was to determine whether severity measures of obstructive sleep apnea (OSA) are associated with arterial stiffness and central blood pressure (two important cardiovascular risk factors) in a large group of patients with OSA.

METHODS

Baseline data from six studies on OSA in which arterial stiffness and central aortic blood pressure measures were determined using applanation tonometry were pooled. Associations between measures of arterial stiffness (heart rate corrected augmentation index [AI75]), central aortic blood pressure (central systolic pressure [CSP] and heart rate corrected central augmentation pressure [CAP75]) and measures of OSA severity were explored using stepwise regression modelling.

RESULTS

Data from 362 participants (M:F ratio 13:1) with mean (standard deviation) age 49.2 (11.0) years, body mass index 31.9 (5.3) kg/m², apnea-hypopnea index (AHI) 35.7 (20.7) events/h were included in the analyses. The AHI, oxygen desaturation index (ODI3%), and sleep time with SpO₂ < 90% (T90) were all associated with arterial stiffness (AI75), (AHI: adj. β = .069; P = .01; ODI3%: adj. β = .072; P = .01; T90: adj. β = .18; P < .0001) and CAP75 (AHI: adj. β = .030; P = .01; ODI3%: adj. β = .027; P = .02; T90: adj. β = .080; P < .0001). AHI was also associated with CSP (AHI: adj. β = .11; P = .002).

CONCLUSIONS

OSA severity was significantly associated with augmentation index and CAP75 although the relationships were not strong.

Pharyngeal distensibility during expiration is an independent predictor of the severity of obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Pharyngeal distensibility and collapsibility reflect the passive properties of tissue in the airway, are an indicator of the ease with which an airway can be deformed and are related to the severity of obstructive sleep apnoea (OSA). During normal tidal respiration, the collapsibility of the pharynx during expiration is passive without confounding by neuromuscular activation that occurs during inspiration. We evaluated the distensibility and collapsibility of the upper airway in subjects with OSA during wakefulness using sophisticated dynamic computed tomography (CT) imaging. We hypothesized that the dynamic changes of the upper airway during expiration would be related to the severity of OSA.

METHODS

Twenty-three patients with OSA and eight normal subjects underwent simultaneous measurement of respiratory flow and airway calibre using ultrafast CT. The change in pharyngeal cross-sectional area divided by the change in concomitant flow (as distensibility or collapsibility) was measured and compared across different severities of OSA.

RESULTS

The slope of this relationship between delta area and delta flow during expiration was significantly higher in severe OSA when compared with normal controls and mild-moderate OSA. Differences in airway distensibility or collapsibility between severity groups were significant in expiration but not in inspiration. Distensibility or collapsibility contributed most to the apnoea-hypopnoea index in regression modelling. Age, gender, and body mass index (BMI) were not significant independent predictors.

CONCLUSION

Our study demonstrates that airway distensibility during the expiratory phase of awake respiration is correlated with the severity of OSA.

Recognizable clinical subtypes of obstructive sleep apnea across international sleep centers: a cluster analysis

Study Objectives

A recent study of patients with moderate-severe obstructive sleep apnea (OSA) in Iceland identified three clinical clusters based on symptoms and comorbidities. We sought to verify this finding in a new cohort in Iceland and examine the generalizability of OSA clusters in an international ethnically diverse cohort.

Methods

Using data on 972 patients with moderate-severe OSA (apnea-hypopnea index [AHI] ≥ 15 events per hour) recruited from the Sleep Apnea Global Interdisciplinary Consortium (SAGIC), we performed a latent class analysis of 18 self-reported symptom variables, hypertension, cardiovascular disease, and diabetes.

Results

The original OSA clusters of disturbed sleep, minimally symptomatic, and excessively sleepy replicated among 215 SAGIC patients from Iceland. These clusters also generalized to 757 patients from five other countries. The three clusters had similar average AHI values in both Iceland and the international samples, suggesting clusters are not driven by OSA severity; differences in age, gender, and body mass index were also generally small. Within the international sample, the three original clusters were expanded to five optimal clusters: three were similar to those in Iceland (labeled disturbed sleep, minimal symptoms, and upper airway symptoms with sleepiness) and two were new, less symptomatic clusters (labeled upper airway symptoms dominant and sleepiness dominant). The five clusters showed differences in demographics and AHI, although all were middle-aged (44.6-54.5 years), obese (30.6-35.9 kg/m2), and had severe OSA (42.0-51.4 events per hour) on average.

Conclusions

Results confirm and extend previously identified clinical clusters in OSA. These clusters provide an opportunity for a more personalized approach to the management of OSA.

Obstructive Sleep Apnea Activates HIF-1 in a Hypoxia Dose-Dependent Manner in HCT116 Colorectal Carcinoma Cells

Obstructive sleep apnea (OSA) affects a significant proportion of the population and is linked to increased rates of cancer development and a worse cancer outcome. OSA is characterized by nocturnal intermittent hypoxia and animal models of OSA-like intermittent hypoxia show increased tumor growth and metastasis. Advanced tumors typically have regions of chronic hypoxia, activating the transcription factor, HIF-1, which controls the expression of genes involved in cancer progression. Rapid intermittent hypoxia from OSA has been proposed to increase HIF-1 activity and this may occur in tumors. The effect of exposing a developing tumor to OSA-like intermittent hypoxia is largely unknown. We have built a cell-based model of physiological OSA tissue oxygenation in order to study the effects of intermittent hypoxia in HCT116 colorectal cancer cells. We found that HIF-1α increases following intermittent hypoxia and that the expression of HIF-target genes increases, including those involved in glycolysis, the hypoxic pathway and extracellular matrix remodeling. Expression of these genes acts as a 'hypoxic' signature which is associated with a worse prognosis. The total dose of hypoxia determined the magnitude of change in the hypoxic signature rather than the frequency or duration of hypoxia-reoxygenation cycles per se. Finally, transcription of HIF1A mRNA differs in response to chronic and intermittent hypoxia suggesting that HIF-1α may be regulated at the transcriptional level in intermittent hypoxia and not just by the post-translational oxygen-dependent degradation pathway seen in chronic hypoxia.

From CPAP to tailored therapy for obstructive sleep Apnoea

Obstructive Sleep Apnoea (OSA) is a common sleep disorder that is associated with daytime symptoms and a range of comorbidity and mortality. Continuous Positive Airway Pressure (CPAP) therapy is highly efficacious at preventing OSA when in use and has long been the standard treatment for newly diagnosed patients. However, CPAP therapy has well recognised limitations in real world effectiveness due to issues with patient acceptance and suboptimal usage. There is a clear need to enhance OSA treatment strategies and options. Although there are a range of alternative treatments (e.g. weight loss, oral appliances, positional devices, surgery, and emerging therapies such as sedatives and oxygen), generally there are individual differences in efficacy and often OSA will not be completely eliminated. There is increasing recognition that OSA is a heterogeneous disorder in terms of risk factors, clinical presentation, pathophysiology and comorbidity. Better characterisation of OSA heterogeneity will enable tailored approaches to therapy to ensure treatment effectiveness. Tools to elucidate individual anatomical and pathophysiological phenotypes in clinical practice are receiving attention. Additionally, recognising patient preferences, treatment enhancement strategies and broader assessment of treatment effectiveness are part of tailoring therapy at the individual level. This review provides a narrative of current treatment approaches and limitations and the future potential for individual tailoring to enhance treatment effectiveness.

From CPAP to tailored therapy for obstructive sleep apnoea

Obstructive Sleep Apnoea (OSA) is a common sleep disorder that is associated with daytime symptoms and a range of comorbidity and mortality. Continuous Positive Airway Pressure (CPAP) therapy is highly efficacious at preventing OSA when in use and has long been the standard treatment for newly diagnosed patients. However, CPAP therapy has well recognised limitations in real world effectiveness due to issues with patient acceptance and suboptimal usage. There is a clear need to enhance OSA treatment strategies and options. Although there are a range of alternative treatments (e.g. weight loss, oral appliances, positional devices, surgery, and emerging therapies such as sedatives and oxygen), generally there are individual differences in efficacy and often OSA will not be completely eliminated. There is increasing recognition that OSA is a heterogeneous disorder in terms of risk factors, clinical presentation, pathophysiology and comorbidity. Better characterisation of OSA heterogeneity will enable tailored approaches to therapy to ensure treatment effectiveness. Tools to elucidate individual anatomical and pathophysiological phenotypes in clinical practice are receiving attention. Additionally, recognising patient preferences, treatment enhancement strategies and broader assessment of treatment effectiveness are part of tailoring therapy at the individual level. This review provides a narrative of current treatment approaches and limitations and the future potential for individual tailoring to enhance treatment effectiveness.

Awake Multimodal Phenotyping for Prediction of Oral Appliance Treatment Outcome

STUDY OBJECTIVES

An oral appliance (OA) is a validated treatment for obstructive sleep apnea (OSA). However, therapeutic response is not certain in any individual and is a clinical barrier to implementing this form of therapy. Therefore, accurate and clinically applicable prediction methods are needed. The goal of this study was to derive prediction models based on multiple awake assessments capturing different aspects of the pharyngeal response to mandibular advancement. We hypothesized that a multimodal model would provide robust prediction.

METHODS

Patients with OSA (apnea-hypopnea index [AHI] > 10 events/h) were recruited for treatment with a customized OA (n = 142, 59% male). Participants underwent facial photography (craniofacial structure), spirometry (mid-inspiratory flow at 50% vital capacity [MIF₅₀] and mid-expiratory flow at 50% vital capacity [MEF₅₀] and the ratio MEF₅₀/MIF₅₀) and nasopharyngoscopy (velopharyngeal collapse with Mueller maneuver and mandibular advancement). Treatment response was defined by 3 criteria: (1) AHI < 5 events/h plus ≥ 50% reduction, (2) AHI < 10 events/h plus ≥ 50% reduction, (3) ≥ 50% AHI reduction. Multivariable regression models were used to assess predictive utility of phenotypic assessments compared to clinical characteristics alone (age, sex, obesity, baseline AHI).

RESULTS

Craniofacial structure and flow-volume loops predicted treatment response. Accuracy of the prediction models (area under the receiver operating characteristic curve) for each criterion were 0.90 (criterion 1), 0.79 (criterion 2), and 0.78 (criterion 3). However, these prediction models including phenotypic assessments did not provide a statistically significant improvement over clinical predictors only.

CONCLUSIONS

Multimodal awake phenotyping does not enhance OA treatment outcome prediction. These office-based, awake assessments have limited utility for robust clinical prediction models. Future work should focus on sleep-related assessments.

COMMENTARY

A commentary on this article appears in this issue on page 1837.

CLINICAL TRIAL REGISTRATION

Registry: Australian New Zealand Clinical Trials Registry, Title: Multimodal phenotyping for the prediction of oral appliance treatment outcome in obstructive sleep apnoea, Identifier: ACTRN12611000409976, URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=336663.

A consensus opinion amongst stakeholders as to benefits of obstructive sleep apnoea treatment for cardiovascular health

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea (OSA) is a prevalent sleep disorder associated with increased cardiovascular morbidity and mortality. Whether treatment of OSA improves cardiovascular risk remains controversial. Our aim was to determine a consensus opinion of key sleep medicine stakeholder groups as to the cardiovascular benefits of treating moderate-severe OSA.

METHODS

A multidisciplinary panel was assembled from representatives from the Australasian Sleep Association, Sleep Health Foundation, Australasian Sleep Technologists Association, the Sleep Health Foundation Business Council and the Sleep Disorders Australia patient support group. Three statements reflecting areas of controversy related to cardiovascular benefits of OSA treatment were created. A modified RAND/UCLA appropriateness methodology was applied determining the panel's level of consensus and agreement with each statement.

RESULTS

Voting results indicated the panel: (1) remained unsure whether moderate-severe OSA treatment improves rates of cardiovascular events/death, (2) agreed that moderate-severe OSA treatment improves blood pressure in patients with hypertension and (3) mostly agreed that moderate-severe OSA treatment improves left ventricular function in patients with heart failure. Consensus of opinion was achieved for statements (1) and (2), but was narrowly missed for statement (3).

CONCLUSION

The panel believed that findings from large-scale randomized trials indicate that treatment of moderate-severe OSA has not been established to improve cardiovascular event or morbidity/mortality rates. Strong evidence supports the ability of treatment to reduce blood pressure. Whilst many panel members believed that treatment improves left ventricular function, some were uncertain of the clinical significance of this secondary endpoint measure derived from lesser quality evidence.

Home sleep apnea testing: comparison of manual and automated scoring across international sleep centers

PURPOSE

To determine the agreement between the manual scoring of home sleep apnea tests (HSATs) by international sleep technologists and automated scoring systems.

METHODS

Fifteen HSATs, previously recorded using a type 3 monitor, were saved in European Data Format. The studies were scored by nine experienced technologists from the sleep centers of the Sleep Apnea Global Interdisciplinary Consortium (SAGIC) using the locally available software. Each study was scored separately by human scorers using the nasal pressure (NP), flow derived from the NP signal (transformed NP), or respiratory inductive plethysmography (RIP) flow. The same procedure was followed using two automated scoring systems: Remlogic (RLG) and Noxturnal (NOX).

RESULTS

The intra-class correlation coefficients (ICCs) of the apnea-hypopnea index (AHI) scoring using the NP, transformed NP, and RIP flow were 0.96 [95% CI 0.93-0.99], 0.98 [0.96-0.99], and 0.97 [0.95-0.99], respectively. Using the NP signal, the mean differences in AHI between the average of the manual scoring and the automated systems were - 0.9 ± 3.1/h (AHI_RLG vs AHI_MANUAL) and - 1.3 ± 2.6/h (AHI_NOX vs AHI_MANUAL). Using the transformed NP, the mean differences in AHI were - 1.9 ± 3.3/h (AHI_RLG vs AHI_MANUAL) and 1.6 ± 3.0/h (AHI_NOX vs AHI_MANUAL). Using the RIP flow, the mean differences in AHI were - 2.7 ± 4.5/h (AHI_RLG vs AHI_MANUAL) and 2.3 ± 3.4/h (AHI_NOX vs AHI_MANUAL).

CONCLUSIONS

There is very strong agreement in the scoring of the AHI for HSATs between the automated systems and experienced international technologists. Automated scoring of HSATs using commercially available software may be useful to standardize scoring in future endeavors involving international sleep centers.

Craniofacial Phenotyping in Chinese and Caucasian Patients With Sleep Apnea: Influence of Ethnicity and Sex

STUDY OBJECTIVES

Craniofacial abnormalities are a risk factor for obstructive sleep apnea (OSA). We have previously shown that phenotypic information derived from craniofacial photographs predict OSA in sleep clinic populations. However, there are likely ethnic and sex differences in craniofacial phenotypes related to OSA. We aimed to assess the use of craniofacial photography to identify interactions between OSA, ethnicity, and sex in craniofacial phenotype.

METHODS

Frontal and profile craniofacial photographs were analyzed from two sleep clinic populations of different ethnicity (Hong Kong Chinese, Australian Caucasians). OSA was defined as apnea-hypopnea index (AHI) > 10 events/h. Ten craniofacial measurements (three angles relating to jaw position and seven ratios describing proportions of the face) were examined for interactions between OSA status and sex or ethnicity) using factorial analysis of variance.

RESULTS

A total of 363 subjects (25% female) were included (n = 200 Chinese, n = 163 Caucasian), of which 33% were controls. There were two-way interactions for OSA with both sex (mandibular plane angle [F = 7.0, P = .009], face / eye width ratio [F = 4.7, P = .032], maxillary / mandibular volume ratio [F = 9.2, P = .003]) and ethnicity (face / nose width ratio [F = 4.0, P = .045], mandibular width / length ratio [F = 5.1, P = .024], maxillary / mandibular volume ratio [F = 11.0, P = .001]).

CONCLUSIONS

We provide evidence of ethnic and sex differences in facial phenotype related to OSA. Furthermore, we demonstrate that craniofacial photography can be used as a phenotypic tool to assess these differences and allow investigation of OSA phenotypes in large samples. This has relevance to personalizing OSA recognition strategies across different populations.

Three-dimensional photography for the evaluation of facial profiles in obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Craniofacial structure is an important determinant of obstructive sleep apnoea (OSA) syndrome risk. Three-dimensional stereo-photogrammetry (3dMD) is a novel technique which allows quantification of the craniofacial profile. This study compares the facial images of OSA patients captured by 3dMD to three-dimensional computed tomography (3-D CT) and two-dimensional (2-D) digital photogrammetry. Measurements were correlated with indices of OSA severity.

METHODS

Thirty-eight patients diagnosed with OSA were included, and digital photogrammetry, 3dMD and 3-D CT were performed. Distances, areas, angles and volumes from the images captured by three methods were analysed.

RESULTS

Almost all measurements captured by 3dMD showed strong agreement with 3-D CT measurements. Results from 2-D digital photogrammetry showed poor agreement with 3-D CT. Mandibular width, neck perimeter size and maxillary volume measurements correlated well with the severity of OSA using all three imaging methods. Mandibular length, facial width, binocular width, neck width, cranial base triangle area, cranial base area 1 and middle cranial fossa volume correlated well with OSA severity using 3dMD and 3-D CT, but not with 2-D digital photogrammetry.

CONCLUSION

3dMD provided accurate craniofacial measurements of OSA patients, which were highly concordant with those obtained by CT, while avoiding the radiation associated with CT.

Qualitative assessment of awake nasopharyngoscopy for prediction of oral appliance treatment response in obstructive sleep apnoea

PURPOSE

Clinical methods to identify responders to oral appliance (OA) therapy for obstructive sleep apnoea (OSA) are needed. Awake nasopharyngoscopy during mandibular advancement, with image capture and subsequent processing and analysis, may predict treatment response. A qualitative assessment of awake nasopharyngoscopy would be simpler for clinical practice. We aimed to determine if a qualitative classification system of nasopharyngoscopic observations reflects treatment response.

METHODS

OSA patients were recruited for treatment with a customised two-piece OA. A custom scoring sheet was used to record observations of the pharyngeal airway (velopharynx, oropharynx, hypopharynx) during supine nasopharyngoscopy in response to mandibular advancement and performance of the Müller manoeuvre. Qualitative scores for degree (< 25%, 25-50%, 50-75%, > 75%), collapse pattern (concentric, anteroposterior, lateral) and diameter change (uniform, anteroposterior, lateral) were recorded. Treatment outcome was confirmed by polysomnography after a titration period of 14.6 ± 9.8 weeks. Treatment response was defined as (1) Treatment AHI < 5, (2) Treatment AHI < 10 plus > 50% AHI reduction and (3) > 50% AHI reduction.

RESULTS

Eighty OSA patients (53.8% male) underwent nasopharyngoscopy. The most common naspharyngoscopic observation with mandibular advancement was a small (< 50%) increase in velopharyngeal lateral diameter (37.5%). The majority of subjects (72.5%) were recorded as having > 75% velopharyngeal collapse on performance of the Müller manoeuvre. Mandibular advancement reduced the observed level of pharyngeal collapse at all three pharyngeal regions (p < 0.001). None of the nasopharyngoscopic qualitative scores differed between responder and non-responder groups.

CONCLUSION

Qualitative assessment of awake nasopharyngoscopy appears useful for assessing the effect of mandibular advancement on upper airway collapsibility. However, it is not sensitive enough to predict oral appliance treatment outcome.

Adherence to Positive Airway Therapy After Switching From CPAP to ASV: A Big Data Analysis

STUDY OBJECTIVES

There is a lack of data regarding adherence trajectories when switching from continuous positive airway pressure (CPAP) to adaptive servoventilation (ASV) in the context of persistent or treatment-emergent central sleep apnea (CSA). This study investigated 90-day adherence rates in patients with sleep apnea based on the type of positive airway pressure (PAP) device used and any switching of PAP modality over time.

METHODS

Telemonitoring data were obtained from a United States PAP database. Eligible patients were a 30% random sample who started PAP, plus all who started ASV, from January 1, 2015 to October 2, 2015. All received PAP and had at least one session with usage of 1 hour or more. Adherence and device usage were determined in three groups: started on CPAP and stayed on CPAP (CPAP only); started on ASV and stayed on ASV (ASV only); started on CPAP, switched to ASV (Switch). The United States Medicare definition of adherence was used.

RESULTS

The study included 198,890 patients; 189,724 (CPAP only), 8,957 (ASV only) and 209 (Switch). In the Switch group, average apnea-hypopnea index decreased significantly on ASV versus CPAP. At 90 days, adherence rates were 73.8% and 73.2% in the CPAP only and ASV only groups. In the Switch group, CPAP adherence was 62.7%, improving to 76.6% after the switch to ASV. Mean device usage at 90 days was 5.27, 5.31, and 5.73 h/d in the CPAP only, ASV only, and Switch groups, respectively.

CONCLUSIONS

Treatment-emergent or persistent CSA during CPAP reduced therapy adherence, but adherence improved early after switching from CPAP to ASV.

Magnetic resonance imaging of the upper airway in patients with quadriplegia and obstructive sleep apnea

The aim of this study was to investigate upper airway anatomy in quadriplegics with obstructive sleep apnea. Fifty subjects were recruited from three hospitals in Australia: people with quadriplegia due to spinal cord injury and obstructive sleep apnea (n = 11), able-bodied people with obstructive sleep apnea (n = 18), and healthy, able-bodied controls (n = 19). All underwent 3-Tesla magnetic resonance imaging of their upper airway. A subgroup (n = 34) received a topical vasoconstrictor, phenylephrine and post-phenylephrine magnetic resonance imaging. Mixed-model analysis indicated no significant differences in total airway lumen volume between the three groups (P = 0.086). Spinal cord injury-obstructive sleep apnea subjects had a significantly larger volume of soft palate (P = 0.020) and retroglossal lateral pharyngeal walls (P = 0.043) than able-bodied controls. Able-bodied-obstructive sleep apnea subjects had a smaller mandible volume than spinal cord injury-obstructive sleep apnea subjects and able-bodied control subjects (P = 0.036). No differences were seen in airway length between groups when controlling for height (P = 0.055). There was a marginal increase in velopharyngeal volume across groups post-phenylephrine (P = 0.050), and post hoc testing indicated the difference was confined to the able-bodied-obstructive sleep apnea group (P < 0.001). No other upper airway structures showed significant changes with phenylephrine administration. In conclusion, people with obstructive sleep apnea and quadriplegia do not have a structurally smaller airway than able-bodied subjects. They did, however, have greater volumes of soft palate and lateral pharyngeal walls, possibly due to greater neck fat deposition. The acute response to upper airway topical vasoconstriction was not enhanced in those with obstructive sleep apnea and quadriplegia. Changes in upper airway anatomy likely contribute to the high incidence in obstructive sleep apnea in quadriplegic subjects.

Trajectories of Emergent Central Sleep Apnea During CPAP Therapy

BACKGROUND

The emergence of central sleep apnea (CSA) during positive airway pressure (PAP) therapy has been observed clinically in approximately 10% of obstructive sleep apnea titration studies. This study assessed a PAP database to investigate trajectories of treatment-emergent CSA during continuous PAP (CPAP) therapy.

METHODS

U.S. telemonitoring device data were analyzed for the presence/absence of emergent CSA at baseline (week 1) and week 13. Defined groups were as follows: obstructive sleep apnea (average central apnea index [CAI] < 5/h in week 1, < 5/h in week 13); transient CSA (CAI ≥ 5/h in week 1, < 5/h in week 13); persistent CSA (CAI ≥ 5/h in week 1, ≥ 5/h in week 13); emergent CSA (CAI < 5/h in week 1, ≥ 5/h in week 13).

RESULTS

Patients (133,006) used CPAP for ≥ 90 days and had ≥ 1 day with use of ≥ 1 h in week 1 and week 13. The proportion of patients with CSA in week 1 or week 13 was 3.5%; of these, CSA was transient, persistent, or emergent in 55.1%, 25.2%, and 19.7%, respectively. Patients with vs without treatment-emergent CSA were older, had higher residual apnea-hypopnea index and CAI at week 13, and more leaks (all P < .001). Patients with any treatment-emergent CSA were at higher risk of therapy termination vs those who did not develop CSA (all P < .001).

CONCLUSIONS

Our study identified a variety of CSA trajectories during CPAP therapy, identifying several different clinical phenotypes. Identification of treatment-emergent CSA by telemonitoring could facilitate early intervention to reduce the risk of therapy discontinuation and shift to more efficient ventilator modalities.

The Effect of Treatment of Obstructive Sleep Apnea on Glycemic Control in Type 2 Diabetes

RATIONALE

There is uncertainty about the effects of treating obstructive sleep apnea on glycemic control in patients with type 2 diabetes.

OBJECTIVES

To determine whether treatment of obstructive sleep apnea in patients with type 2 diabetes improves glycemic control.

METHODS

In this trial, we randomized patients with type 2 diabetes and no previous diagnosis of obstructive sleep apnea, with a glycated hemoglobin level of 6.5-8.5%, and an oxygen desaturation index of 15 or more events per hour to positive airway pressure therapy or to usual care.

MEASUREMENTS AND MAIN RESULTS

A total of 416 patients met the entry criteria as determined by each site and were randomized. Of the 298 participants who met centrally adjudicated entry criteria, no differences between the study groups were seen for change in glycated hemoglobin. Furthermore, there were no between-group differences when analyses were restricted to those with poorer baseline glycemic control, those with more severe sleep apnea, or those who were adherent to therapy. A greater fall in diastolic blood pressure occurred in the positive airway pressure group than in the usual care group (-3.5 mm Hg vs. -1.5 mm Hg; P = 0.07). This difference was significant in those who were adherent to positive airway pressure therapy (-4.4 mm Hg vs. -1.6 mm Hg; P = 0.02). There was a significant reduction in sleepiness in the positive airway pressure therapy group (P < 0.0001). Quality of life assessment revealed improvements in vitality, mental health, and mental component summary scores in the positive airway pressure therapy group.

CONCLUSIONS

This trial showed no effect of positive airway pressure therapy on glycemic control in patients with relatively well-controlled type 2 diabetes and obstructive sleep apnea. Clinical trial registered with www.clinicaltrials.gov (NCT00509223).

P4 medicine approach to obstructive sleep apnoea

P4 medicine is an evolving approach to personalized medicine. The four Ps offer a means to: Predict who will develop disease and co-morbidities; Prevent rather than react to disease; Personalize diagnosis and treatment; have patients Participate in their own care. P4 medicine is very applicable to obstructive sleep apnoea (OSA) because each OSA patient has a different pathway to disease and its consequences. OSA has both structural and physiological mechanisms with different clinical subgroups, different molecular profiles and different consequences. This may explain why there are different responses to alternative therapies, such as intraoral devices and hypoglossal nerve stimulation therapy. Currently, technology facilitates patients to participate in their own care from screening for OSA (snoring and apnoea apps) to monitoring response to therapy (sleep monitoring, blood pressure, oxygen saturation and heart rate) as well as monitoring their own continuous positive airway pressure (CPAP) compliance. We present a conceptual framework that provides the basis for a new, P4 medicine approach to OSA and should be considered more in depth: predict and prevent those at high risk for OSA and consequences, personalize the diagnosis and treatment of OSA and build in patient participation to manage OSA.

Differences in respiratory arousal threshold in Caucasian and Chinese patients with obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Ethnic differences in obstructive sleep apnoea (OSA) phenotype may not be limited to obesity and craniofacial factors. The aims of the study were to (i) compare the proportion of Caucasians and Chinese patients with a low respiratory arousal threshold (ArTH) and (ii) explore the influence of anatomical compromise on ArTH.

METHODS

Interethnic comparison was conducted between cohorts of Caucasian and Chinese patients from specialist sleep disorder clinics. Polysomnography and craniofacial photography were performed. A low respiratory ArTH was determined by an ArTH score of 2 or above (one point for each: apnoea-hypopnoea index (AHI) < 30/h, nadir oxygen saturation (SaO₂ ) > 82.5%, fractions of hypopnoeas > 58.3%). Anatomical compromise was stratified according to the photographic face width measurement.

RESULTS

A total of 348 subjects (163 Caucasians and 185 Chinese) were analysed. There was a significantly lower proportion of Chinese patients with moderate-severe OSA (AHI ≥ 15) who had a low ArTH (28.4% vs 48.8%, P = 0.004). This difference remained significant among those with severe OSA (AHI ≥ 30) (2.6% vs 17.1%, P = 0.02). The proportion of moderate-severe OSA Caucasians with a low ArTH was significantly less in those with severe anatomical compromise (36.6% vs 61.0%, P = 0.03), whereas there was no difference in Chinese patients (25.5% vs 31.5%, P = 0.49).

CONCLUSION

Compared to Caucasians with severe OSA, a low respiratory ArTh appears to be a less common pathophysiological mechanism in Chinese patients. Caucasians with less severe anatomical compromise exhibit evidence of a lower ArTh, an association which is absent in Chinese patients. Our data suggest that OSA mechanisms may vary across racial groups.

Performance of Remotely Controlled Mandibular Protrusion Sleep Studies for Prediction of Oral Appliance Treatment Response

STUDY OBJECTIVES

Mandibular protrusion during sleep monitoring has been proposed as a method to predict oral appliance treatment outcome. A commercial remotely controlled mandibular protrusion (RCMP) device has become available for this purpose with predictive accuracy demonstrated in an initial study. Our aim was to validate this RCMP method for oral appliance treatment outcome prediction in a clinical sleep laboratory setting.

METHODS

Forty-two obstructive sleep apnea (OSA) patients (apnea-hypopnea index [AHI] > 10 events/h) were recruited to undergo a RCMP sleep study before commencing oral appliance treatment. The RCMP study was used to make a prediction of treatment "Success" or "Failure" based on a rule of ≤ 1 respiratory event per 5 min supine rapid eye movement sleep. Oral appliance treatment response was verified by polysomonography and defined as treatment AHI < 10 events/h with 50% reduction.

RESULTS

Participants were on average middle-aged (57.1 ± 11.6 y) and overweight (29.6 ± 4.5 kg/m²) with baseline AHI 31.5 ± 20.5 events/h, 39% severe OSA (AHI > 30 events/h). Two participants (5%) were not able to tolerate the RCMP study. Oral appliance treatment outcome was verified in 33 participants (RCMP results: "Success" n = 10, "Failure" n = 15, "Inconclusive" n = 8). In those with a treatment outcome prediction (n = 25) the diagnostic characteristics of the RCMP test were sensitivity 81.8%, specificity 92.9%, positive predictive value 90%, and negative predictive value 86.7% (n = 3 misclassified).

CONCLUSIONS

The RCMP device was well tolerated by patients and successfully used to perform mandibular protrusion sleep studies in our sleep laboratory. The RCMP sleep study showed good accuracy as a prediction technique for oral appliance treatment outcome, although there was a high rate of inconclusive tests.

Agreement in the Scoring of Respiratory Events Among International Sleep Centers for Home Sleep Testing

STUDY OBJECTIVES

Home sleep testing (HST) is used worldwide to confirm the presence of obstructive sleep apnea (OSA). We sought to determine the agreement of HST scoring among international sleep centers.

METHODS

Fifteen HSTs, previously recorded using a type 3 monitor, were deidentified and saved in European Data Format. The studies were scored by nine technologists from the sleep centers of the Sleep Apnea Global Interdisciplinary Consortium (SAGIC) using the locally available software. Each study was scored separately using one of three different airflow signals: nasal pressure (NP), transformed (square root) nasal pressure signal (transformed NP), and uncalibrated respiratory inductive plethysmography (RIP) flow. Only one of the three airflow signals was visible to the scorer at each scoring session. The scoring procedure was repeated to determine the intrarater reliability.

RESULTS

The intraclass correlation coefficients (ICCs) using the NP were: apnea-hypopnea index (AHI) = 0.96 (95% confidence interval [CI]: 0.93-0.99); apnea index = 0.91 (0.83-0.96); and hypopnea index = 0.75 (0.59-0.89). The ICCs using the transformed NP were: AHI = 0.98 (0.96-0.99); apnea index = 0.95 (0.90-0.98); and hypopnea index = 0.90 (0.82-0.96). The ICCs using the RIP flow were: AH I = 0.98 (0.96-0.99); apnea index = 0.66 (0.48-0.84); and hypopnea index = 0.78 (0.63-0.90). The mean difference of first and second scoring sessions of the same respiratory variables ranged from -1.02 to 0.75/h.

CONCLUSION

There is a strong agreement in the scoring of the respiratory events for HST among international sleep centers. Our results suggest that centralized scoring of HSTs may not be necessary in future research collaboration among international sites.

COMMENTARY

A commentary on this article appears in this issue on page 7.

Obstructive sleep apnoea and quality of life in Ehlers-Danlos syndrome: a parallel cohort study

BACKGROUND

Patients with the connective tissue disorder Ehlers-Danlos syndrome (EDS) often suffer from fatigue, excessive daytime sleepiness and impaired quality of life. Obstructive sleep apnoea (OSA) may be an underlying cause for these symptoms but its prevalence in this population is unclear.

METHODS

In this prospective parallel-cohort study, we included 100 adult patients with EDS (46% hypermobile-type, 35% classical-type and 19% other), which were one-to-one matched to 100 healthy adult controls according to sex, age, weight and height. Participants underwent structured interviews (including short-form 36) and level-3 respiratory polygraphy. OSA was defined as apnoea-hypopnea index ≥5/hour. Photographic craniofacial phenotyping was conducted in a subgroup. Conditional logistic regression was used to compare the prevalence of OSA.

RESULTS

In patients with EDS, OSA prevalence was 32% versus 6% in the matched control group (OR 5.3 (95% CI 2.5 to 11.2); p<0.001). The EDS group reported impaired quality of life in all dimensions (p<0.05) and significantly higher excessive daytime sleepiness measured by the Epworth Sleepiness Scale (median (quartiles) 11 (7-14) vs 7 (5-10); p<0.001). OSA severity was positively associated with daytime sleepiness and lower quality of life in the EDS group. There was no evidence of a difference between the two study groups in terms of craniofacial phenotypes.

CONCLUSIONS

The prevalence of OSA is higher in patients with EDS than in a matched control group. This is of clinical relevance as it is associated with fatigue, excessive daytime sleepiness and impaired quality of life. Further studies are needed to assess the clinical benefit of OSA treatment in patients with EDS.

TRIAL REGISTRATION NUMBER

NCT02435745.

Population-Based Study of Sleep Apnea in Pregnancy and Maternal and Infant Outcomes

STUDY OBJECTIVES

To examine the association between sleep apnea and pregnancy outcomes in a large population-based cohort.

METHODS

Population-based cohort study using linked birth and hospital records was conducted in New South Wales, Australia. Participants were all women who gave birth from 2002 to 2012 (n = 636,227). Sleep apnea in the year before pregnancy or during pregnancy was identified from hospital records. Outcomes of interest were gestational diabetes, pregnancy hypertension, planned delivery, caesarean section, preterm birth, perinatal death, 5-minute Apgar score, admission to neonatal intensive care or special care nursery, and infant size for gestational age. Maternal outcomes were identified using a combination of hospital and birth records. Infant outcomes came from the birth record. Modified Poisson regression models were used to examine associations between sleep apnea and each outcome taking into account maternal age, country of birth, socioeconomic disadvantage, smoking, obesity, parity, pre-existing diabetes and hypertension.

RESULTS

Sleep apnea was significantly associated with pregnancy hypertension (adjusted RR 1.43; 95% CI 1.18-1.73), planned delivery (1.15; 1.07-1.23), preterm birth (1.50; 1.21-1.84), 5-minute Apgar < 7 (1.60; 1.07-2.38), admission to neonatal intensive care/special care nursery (1.26; 1.11-1.44), large-for-gestational-age infants (1.27; 1.04-1.55) but not with gestational diabetes (1.09; 0.82-1.46), caesarean section (1.06; 0.96-1.17), perinatal death (1.73; 0.92-3.25), or small-for-gestational-age infants (0.81; 0.61-1.08).

CONCLUSIONS

Sleep apnea is associated with higher rates of obstetric complications and intervention, as well as preterm delivery. Future research should examine if these are independent of obstetric history.

Maxillomandibular Volume Influences the Relationship between Weight Loss and Improvement in Obstructive Sleep Apnea

STUDY OBJECTIVES

Obesity is the major risk factor for OSA; however, weight loss reduces OSA to a variable extent. We aimed to assess whether size of the maxillomandibular skeletal enclosure influences the relationship between weight loss and OSA reduction.

METHODS

Obese males (≥ 30 kg/m2) with moderate-severe OSA (AHI > 15/h) participating in a 6-mo open-label weight loss program had craniofacial computed tomography (CT) scans before and after weight loss. CT scans were analysed using three-dimensional cephalometry. Maxillomandibular volume was calculated from skeletal landmarks on the mandible (condyle, gonion, menton) and maxilla (anterior nasal spine). Multiple regression analysis was used to test for moderating effects of maxillomandibular volume on relationship between changes in weight and apnea-hypopnea index (AHI).

RESULTS

Fifty-two men (age 44.3 ± 8.8 y, AHI 42.9 ± 21.3 events/h, body mass index [BMI] 34.0 ± 2.7 kg/m2) had 7.4 ± 4.1% weight loss and 34.1 ± 32.4% AHI reduction at 6 months. BMI reduction modestly predicted AHI change (r2 = 0.17, P = 0.002). The interaction term of maxillomandibular volume and BMI change was a predictor of OSA improvement (P = 0.03), indicating maxillomandibular volume moderates this relationship. Subgroup analyses of patients by small, medium, and large maxillomandibular volume showed a strong correlation between weight loss and OSA improvement only in the small volume group (r = 0.654, P = 0.004). There was no relationship evident in those with large maxillomandibular volume (r = 0.05, P = 0.9).

CONCLUSION

Maxillomandibular volume influences the relationship between weight loss and OSA improvement with an effect on AHI more evident in those with a smaller craniofacial skeleton.

Oral Appliance Treatment Response and Polysomnographic Phenotypes of Obstructive Sleep Apnea

STUDY OBJECTIVES

Mandibular advancement splints (MAS) are an effective treatment for obstructive sleep apnea (OSA); however, therapeutic response is variable. Younger age, female gender, less obesity, and milder and supine-dependent OSA have variably been associated with treatment success in relatively small samples. Our objective was to utilize a large cohort of MAS treated patients (1) to compare efficacy across patients with different phenotypes of OSA and (2) to assess demographic, anthropometric, and polysomnography variables as treatment response predictors.

METHODS

Retrospective analysis of MAS-treated patients participating in clinical trials in sleep centers in Sydney, Australia between years 2000-2013. All studies used equivalent customized two-piece MAS devices and treatment protocols. Treatment response was defined as (1) apnea-hypopnea index (AHI) < 5/h, (2) AHI < 10/h and ≥ 50% reduction, and (3) ≥ 50% AHI reduction.

RESULTS

A total of 425 patients (109 female) were included (age 51.2 ± 10.9 years, BMI 29.2 ± 5.0 kg/m2). MAS reduced AHI by 50.3% ± 50.7% across the group. Supine-predominant OSA patients had lower treatment response rates than non-positional OSA (e.g., 36% vs. 59% for AHI < 10/h). REM-predominant OSA showed a lower response rate than either NREM or non-stage dependent OSA. In prediction modelling, age, baseline AHI, and anthropometric variables were predictive of MAS treatment outcome but not OSA phenotype. Gender was not associated with treatment outcome.

CONCLUSION

Lower MAS treatment response rates were observed in supine and REM sleep. In a large sample, we confirm that demographic, anthropometric, and polysomnographic data only weakly inform about MAS efficacy, supporting the need for alternative objective prediction methods to reliably select patients for MAS treatment.

CPAP pressure for prediction of oral appliance treatment response in obstructive sleep apnea

STUDY OBJECTIVES

Mandibular advancement splints (MAS) are often preferred to CPAP treatment for OSA but are not always equally efficacious. High therapeutic CPAP pressure has been associated with MAS treatment failure in a Japanese population. We sought to assess the relationship between CPAP pressure and MAS treatment response in an Australian population.

METHODS

Therapeutic CPAP pressure and MAS treatment response were obtained from a one-month crossover trial of both treatments. Predictive utility of CPAP pressure to identify MAS treatment response was assessed.

RESULTS

Seventy-eight OSA patients were included (age 49.3 ± 11.1 years, BMI 29.1 ± 5.8 kg/m(2)) with predominantly moderate-severe OSA (AHI 30.0 ± 12.7/h). CPAP pressure was lower in MAS responders (MAS AHI < 10/h) 9.7 ± 1.6 vs. 11.7 ± 2.4 cm H O, p < 0.01, with area under ROC curve of 0.74 (95% CI 0.63-0.86), p < 0.01. The best cutoff value of 10.5 cm H O useful for discriminating MAS responders and non-responders in the previous Japanese population, was inadequate for prediction in the current population (0.47 negative predictive value [NPV]). However a cutoff of 13 cm H O identified MAS non-responders (1.0 NPV). Multivariate regression identified CPAP pressure (odds ratio [95% confidence interval] 0.53 [0.33-0.87], age (0.93 [0.87-0.99]) and AHI (0.92 [0.86-0.97]) as predictors of MAS treatment response (model r(2) = 0.54, p < 0.001).

CONCLUSIONS

In Australian patients, the majority of whom are Caucasian, a higher therapeutic CPAP pressure requirement in conjunction with age and OSA severity characteristics may be useful to indicate likelihood of success with MAS as an alternative therapy.

Facial phenotyping by quantitative photography reflects craniofacial morphology measured on magnetic resonance imaging in Icelandic sleep apnea patients

STUDY OBJECTIVES

(1) To determine whether facial phenotype, measured by quantitative photography, relates to underlying craniofacial obstructive sleep apnea (OSA) risk factors, measured with magnetic resonance imaging (MRI); (2) To assess whether these associations are independent of body size and obesity.

DESIGN

Cross-sectional cohort.

SETTING

Landspitali, The National University Hospital, Iceland.

PARTICIPANTS

One hundred forty patients (87.1% male) from the Icelandic Sleep Apnea Cohort who had both calibrated frontal and profile craniofacial photographs and upper airway MRI. Mean ± standard deviation age 56.1 ± 10.4 y, body mass index 33.5 ± 5.05 kg/m(2), with on-average severe OSA (apnea-hypopnea index 45.4 ± 19.7 h(-1)).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Relationships between surface facial dimensions (photos) and facial bony dimensions and upper airway soft-tissue volumes (MRI) was assessed using canonical correlation analysis. Photo and MRI craniofacial datasets related in four significant canonical correlations, primarily driven by measurements of (1) maxillary-mandibular relationship (r = 0.8, P < 0.0001), (2) lower face height (r = 0.76, P < 0.0001), (3) mandibular length (r = 0.67, P < 0.0001), and (4) tongue volume (r = 0.52, P = 0.01). Correlations 1, 2, and 3 were unchanged when controlled for weight and neck and waist circumference. However, tongue volume was no longer significant, suggesting facial dimensions relate to tongue volume as a result of obesity.

CONCLUSIONS

Significant associations were found between craniofacial variable sets from facial photography and MRI. This study confirms that facial photographic phenotype reflects underlying aspects of craniofacial skeletal abnormalities associated with OSA. Therefore, facial photographic phenotyping may be a useful tool to assess intermediate phenotypes for OSA, particularly in large-scale studies.

Oral appliance treatment for obstructive sleep apnea: an update

Oral appliances (OA) have emerged as an alternative to continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) treatment. The most commonly used OA reduces upper airway collapse by advancing the mandible (OAm). There is a strong evidence base demonstrating OAm improve OSA in the majority of patients, including some with more severe disease. However OAm are not efficacious for all, with approximately one-third of patients experiencing no therapeutic benefit. OAm are generally well tolerated, although short-term adverse effects during acclimatization are common. Long-term dental changes do occur, but these are for the most part subclinical and do not preclude continued use. Patients often prefer OAm to gold-standard CPAP treatment. Head-to-head trials confirm CPAP is superior in reducing OSA parameters on polysomnography; however, this greater efficacy does not necessarily translate into better health outcomes in clinical practice. Comparable effectiveness of OAm and CPAP has been attributed to higher reported nightly use of OAm, suggesting that inferiority in reducing apneic events may be counteracted by greater treatment adherence. Recently, significant advances in commercially available OAm technologies have been made. Remotely controlled mandibular positioners have the potential to identify treatment responders and the level of therapeutic advancement required in single night titration polysomnography. Objective monitoring of OAm adherence using small embedded temperature sensing data loggers is now available and will enhance clinical practice and research. These technologies will further enhance efficacy and effectiveness of OAm treatment for OSA.

Breastfeeding and snoring: a birth cohort study

OBJECTIVE

To investigate the relationship between breastfeeding and snoring in childhood.

METHODS

In a cohort of children with a family history of asthma who were recruited antenatally we prospectively recorded data on infant feeding practices throughout the first year of life. Snoring status and witnessed sleep apnea were measured at age 8 years by parent-completed questionnaire. Associations were estimated by logistic regression with, and without, adjustment for sets of confounders designed to exclude biasing effects.

RESULTS

Habitual snoring was reported in 18.8% of the sample, and witnessed apnea in 2.7%. Any breastfeeding for longer than one month was associated with a reduced risk of habitual snoring at age 8 (adjusted OR 0.48, 95% CI 0.29 to 0.81) and duration of breastfeeding was inversely associated with the prevalence of habitual snoring (adjusted OR 0.79, 95% CI 0.62 to 1.00). Any breastfeeding for longer than 1 month was associated with a lower risk of witnessed sleep apnea (adjusted OR 0.17, 95% CI 0.04 to 0.71). The protective associations were not mediated by BMI, current asthma, atopy or rhinitis at age 8 years.

CONCLUSIONS

Breastfeeding for longer than one month decreases the risk of habitual snoring and witnessed apneas in this cohort of children with a family history of asthma. The underlying mechanism remains unclear but the finding would be consistent with a beneficial effect of the breast in the mouth on oropharyngeal development with consequent protection against upper airway dysfunction causing sleep-disordered breathing.